1. Field of the Invention
The present invention relates to a seat suspension for underground mining machines. More specifically, the present invention relates to a compact seat suspension which is adapted to be mounted entirely behind a seat and which only allows for limited vertical travel of the seat.
2. Description of the Prior Art
The provision of seat suspensions beneath an operator's or passenger's seat of various types of vehicles is well known. For example, U.S. Pat. No. 4,351,556 discloses the provision of a vertical suspension system which includes springs and shock absorbers for supporting a seat and isolating vertical vibration and dampening of vertical vibration between the chassis and the seat.
Even in the field of mining machines, such as mining shuttle cars, tractors, utility vehicles or other forms of continuous mining machines, seat suspensions located beneath the seat has been utilized on medium and high seam machines. To applicants' knowledge, however, seat suspensions which include springs and shock absorbers have not been utilized on low seam machines for the simple reason that there is often not enough room under the seat in such machines for a suspension.
It is also well known in the art to provide some type of suspension means between an operator's compartment or cab of a mining machine and the mining machine body. Such suspension means are frequently utilized to maintain the operator's compartment a desired height above the floor, or, in some cases, to allow the operator's compartment to rest on the mine floor to minimize the overall height of the operator's compartment. Examples of various types of suspension means utilized for operator's compartments are disclosed in U.S. Pat. Nos. 4,078,629; 4,065,167; 3,678,864; 4,365,682; and 4,275,800. While these patents provide an effective mechanism for supporting and adjusting the relative vertical position of an operator's compartment with respect to the vehicle, these patents do not in any way suggest a solution to the problem of providing a compact seat suspension within the limited space available inside an operator's compartment of a mining machine.